134 FLORENCE R. SABIN 



lenticular nucleus underlies the island of Reil and hence it will 

 be seen that it lies for the most part in front of the thalamus, 

 which is its original position. As seen from the side, the lenticular 

 nucleus or its lateral portion, the putamen, is a great oval mass 

 of cells (fig. 9) ; the antero-posterior diameter is slightly greater 

 than the dorso-ventral, speaking in terms of the cerebrum, and 

 close to the optic nerve is a small tongue of the nucleus which ex- 

 tends into the temporal lobe. In the curve of this tongue is the 

 non-medullated anterior commissure. 



Since the lenticular nucleus is best known as it appears in 

 horizontal sections of the gross brain, it would be most readily 

 understood by a dorsal view of the model, that is, a view taken 

 from the dorsal surface of the cerebrum. The form of the nucleus 

 in the new-born corresponds with its form in the adult as can be 

 seen by comparing the description with horizontal sections of the 

 adult. As seen from the convex surface of the cerebrum, the len- 

 ticular nucleus is a triangular mass, divided into three sections 

 by bands of fibres for the most part non-medullated. The outer 

 division, the putamen, is the largest, it projects farthest toward the 

 dorsal surface of the brain and also extends farthest ventralward. 

 It is crescent in shape with the anterior end much larger than the 

 posterior. Next comes the outer part of the globus pallidus, which 

 is likewise crescent in shape with a swollen anterior end. The inner 

 part of the globus pallidus is rectangular in shape. The medul- 

 lated fibres are all associated with this inner division of the globus 

 paUidus; starting with the median plane, there are a few medul- 

 lated fibres between the anterior end of the two parts of the globus 

 pallidus (no. 48) ; secondly, there is a mass of fibres within the medial 

 part of the globus pallidus at its posterior or caudal end (no. 30) , the 

 fibres lying adjacent to the crus as seen in fig. 4, and thirdly, there 

 is the lateral capsule for the inner division of the globus pallidus 

 which is the place of origin of the lenticular cortical radiation 

 previously described (no. 27). If the lenticular nucleus be now 

 viewed again from the mesial aspect it will be seen that the bands 

 of fibres, for the most part non-medullated, which separate the 

 three divisions, all connect (see 48, fig. 4), with the anterior 

 limb of the internal capsule, so that if these bands of fibres be 



